1. Field of the Invention
This invention relates to longwall coal mining operations, and more particularly to a method of controlling dust around the working face of a longwall mining operation.
2. The Prior Art
Longwall mining is a relatively recently developed technique of mining coal in which a coal seam is developed by driving a series of entries or gate roads through the coal seam to create large generally rectangular longwall pillars which are then mined by a longwall mining machine which traverses a working face extending at right angles to a pair of parallel gate roads. As the mining machine moves through the coal pillar, a row of roof supports is advanced along with the mining machine and its associated cut coal conveyor. Longwall mining is now a well developed and widely used coal mining technique.
One of the problems associated with longwall mining is the generation of large amounts of dust around the working face. This invention is directed to a novel process for reducing the dust level around the working face of a longwall mining operation.
Longwall mining is described in some detail in U.S. Pat. No. 4,196,933, although that patent does not discuss the problem of dust in the working face area.
One prior art approach to controlling dust has been to use spray fans to knock down dust in the air. While successful to some extent, these spray fans create additional operating problems in some cases.
An early version of longwall mining, not widely practiced today, is described in U.S. Pat. No. 2,859,682. In that method, a bore miner produces large bores parallel to the longwall face, and a coal cutting machine then cuts the coal between the bore and the face. Modern longwall mining utilizes the equipment and technique described in U.S. Pat. No. 4,196,933 rather than that described in U.S. Pat. No. 2,859,682.
The mining process described in U.S. Pat. No. 2,859,682 is, however, pertinent to the present invention in that it describes a method of ventilating the working area by flow of air from one gate road through holes in the coal pillar and out another gate road. However, the requirement in U.S. Pat. No. 2,859,682 of bores or tunnels large enough to enter and form smaller cross bores connecting the large bore with the working area is not practical in most cases, and there has been a need for an improved method of controlling dust in the working face area of a longwall mining operation. Such a method is provided by the present invention.